Wierd unwanted painted textures refusing to be deleted
The image shows you deleted the texture brush, but not necessarily the texture material. Check those are all deleted or disabled. If you want to start on a blank image again, just add a new image in the UV window.

From your other image it looks like you are adding each image in a separate material which I assume you wish to use for texturing. You should rather have one material where you can add multiple texture slots - those textures once loaded can be used in the texture brushes. Make sure you save your new image and link it back to the new texture in material tab.